Mathematicians prove Burau representation of braid group is faithful for n=4

A paper published on arXiv claims to prove that the Burau representation of the braid group is faithful for n=4. The faithfulness of this representation has been an open problem in algebraic topology for decades — it was already known to be unfaithful for n≥5, but the n=4 case remained unresolved. The result has attracted attention in the mathematics community.